ct.c, ct.h: New constant-time operations.

[u/mdw/catacomb] / skipjack.c

diff --git a/skipjack.c b/skipjack.c
index 98bb48f..d87f22c 100644 (file)
--- a/skipjack.c
+++ b/skipjack.c
@@ -1,13 +1,13 @@
 /* -*-c-*-
  *
- * $Id: skipjack.c,v 1.3 2000/08/01 00:28:34 mdw Exp $
+ * $Id: skipjack.c,v 1.5 2004/04/08 01:36:15 mdw Exp $
  *
  * The Skipjack block cipher
  *
  * (c) 2000 Straylight/Edgeware
  */
 
-/*----- Licensing notice --------------------------------------------------* 
+/*----- Licensing notice --------------------------------------------------*
  *
  * This file is part of Catacomb.
  *
@@ -15,33 +15,18 @@
  * it under the terms of the GNU Library General Public License as
  * published by the Free Software Foundation; either version 2 of the
  * License, or (at your option) any later version.
- * 
+ *
  * Catacomb is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU Library General Public License for more details.
- * 
+ *
  * You should have received a copy of the GNU Library General Public
  * License along with Catacomb; if not, write to the Free
  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: skipjack.c,v $
- * Revision 1.3  2000/08/01 00:28:34  mdw
- * Performance improvement: read keys in as 32-bit words and deal them out
- * byte-by-byte.
- *
- * Revision 1.2  2000/07/15 20:48:45  mdw
- * Remove some useless tests in the G function.
- *
- * Revision 1.1  2000/07/15 15:39:33  mdw
- * The NSA's Skipjack block cipher.
- *
- */
-
 /*----- Header files ------------------------------------------------------*/
 
 #include <mLib/bits.h>
@@ -57,19 +42,19 @@ const octet skipjack_keysz[] = { KSZ_SET, 10, 0 };
 
 /*----- The Skipjack S-box ------------------------------------------------*/
 
-static octet f[256] = SKIPJACK_S;
+static const octet f[256] = SKIPJACK_S;
 
 /*----- Main code ---------------------------------------------------------*/
 
 /* --- @skipjack_init@ --- *
  *
- * Arguments:   @skipjack_ctx *k@ = pointer to key block
- *              @const void *buf@ = pointer to key buffer
- *              @size_t sz@ = size of key material
+ * Arguments:  @skipjack_ctx *k@ = pointer to key block
+ *             @const void *buf@ = pointer to key buffer
+ *             @size_t sz@ = size of key material
  *
- * Returns:     ---
+ * Returns:    ---
  *
- * Use:         Initializes a Skipjack key buffer.  The key buffer must be
+ * Use:                Initializes a Skipjack key buffer.  The key buffer must be
  *             exactly 10 bytes long.
  */
 
@@ -89,21 +74,21 @@ void skipjack_init(skipjack_ctx *k, const void *buf, size_t sz)
 
 /* --- @skipjack_eblk@, @skipjack_dblk@ --- *
  *
- * Arguments:   @const skipjack_ctx *k@ = pointer to key block
- *              @const uint32 s[2]@ = pointer to source block
- *              @uint32 d[2]@ = pointer to skipjacktination block
+ * Arguments:  @const skipjack_ctx *k@ = pointer to key block
+ *             @const uint32 s[2]@ = pointer to source block
+ *             @uint32 d[2]@ = pointer to skipjacktination block
  *
- * Returns:     ---
+ * Returns:    ---
  *
- * Use:         Low-level block encryption and decryption.
+ * Use:                Low-level block encryption and decryption.
  */
 
 #define G(x, k) do {                                                   \
   octet _x = U8(x >> 8), _y = U8(x);                                   \
   _x ^= f[_y ^ U8(k >> 24)];                                           \
   _y ^= f[_x ^ U8(k >> 16)];                                           \
-  _x ^= f[_y ^ U8(k >>  8)];                                           \
-  _y ^= f[_x ^ U8(k >>  0)];                                           \
+  _x ^= f[_y ^ U8(k >> 8)];                                            \
+  _y ^= f[_x ^ U8(k >> 0)];                                            \
   x = (_x << 8) | _y;                                                  \
 } while (0)
 
@@ -145,8 +130,8 @@ void skipjack_eblk(const skipjack_ctx *k, const uint32 *s, uint32 *d)
 
 #define G_INV(x, k) do {                                               \
   octet _x = U8(x >> 8), _y = U8(x);                                   \
-  _y ^= f[_x ^ U8(k >>  0)];                                           \
-  _x ^= f[_y ^ U8(k >>  8)];                                           \
+  _y ^= f[_x ^ U8(k >> 0)];                                            \
+  _x ^= f[_y ^ U8(k >> 8)];                                            \
   _y ^= f[_x ^ U8(k >> 16)];                                           \
   _x ^= f[_y ^ U8(k >> 24)];                                           \
   x = (_x << 8) | _y;                                                  \